Image capturing apparatus, image processing apparatus and image processing method

ABSTRACT

A digital camera which performs digital processing on an image obtained by image capturing has a three-dimensional lattice point data table for image data conversion processing. The digital camera holds a matrix coefficient set for performing the conversion processing by matrix operation. In the respective lattice points of the three-dimensional lattice point data table, values corresponding to the conversion processing with the matrix coefficient set are set. Then a raw image file, including compressed image data obtained by lossy compression on the image data converted by the conversion processing and the held matrix coefficient set, as attendant information, is generated.

This application is a division of application Ser. No. 11/500,430 filedAug. 8, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to image processing in an image capturingapparatus such as a digital camera.

2. Description of the Related Art

Generally, regarding image processing within digital cameras, inperforming various conversion processing (for example, a gammaconversion) in, 3×3 matrix operation, a one-dimensional look-up tableand the like are used. These conversion processings are appropriate forreducing the amount of hardware memory and gates in chip downsizing, andin scale reduction for energy saving. However; in recent years,advancement in hardware microminiaturization and reductions in IC powersource voltage have allowed, chip size reductions and more effectiveenergy savings to be realized. As a result, it is now possible to mounta complex circuit, a large capacity memory and the like within the IC.Accordingly, it is now becoming possible to perform complex imageprocessing within digital cameras using a three-dimensional look-uptable (hereinbelow, referred to as a “three-dimensional lattice pointdata table”), high-order matrix operation or the like.

However, in many cases, since the number of lattice points and bits areconstrained by the hardware within the IC, high-precision imageprocessing as in the case of application software cannot be performed.Further, when development processing (processing to develop a capturedimage) is performed on raw image data by an application, it is necessaryto record data on the look-up table in an image file obtained by imagecapturing. In this arrangement, the file size of the raw imageincreases. For example, in an m-grid three-dimensional lattice pointdata table, because the number of grids in one dimension is m, the totalnumber of grids is m³. Accordingly, the m-grid three-dimensional datatable (three-dimensional look-up table), where three n-byte values areallotted to the respective grids, requires a capacity of m³×n×3 bytes.More concretely, in a 9-grid 8-bit three-dimensional lattice point datatable requires a capacity of 2187 (=9×9×9×1×3) bytes. In contrast tothis, a 33-grid 16-bit three-dimensional lattice point data tablerequires a hundredfold capacity, 215622 (=33×33×33×2×3) bytes. Further,when there are multiple user-selectable three-dimensional look-uptables, for the subsequent development processing, it is desirable torecord all the three-dimensional look-up tables in a file. In this case,file size is further increased, as well as the time required to save thefile into a memory. As a result, the number of image frames that can becaptured in a series is limited.

U.S. Pat. No. 5,073,818 discloses a printer having a look-up tablecircuit for image processing. According to this U.S. Pat. No. 5,073,818,because the file size increases when the entire look-up table is stored,a look-up table for actual image conversion is generated from correctionfunctions.

However, if all the data is generated using a look-up table for imageprocessing with high bit precision, the data size of the look-up tablebecomes enormous, and the circuit scale increases. Further, to performimage processing using high-order matrix operations for image processingwith high bit precision, a large number of multipliers are required, andwhen the number of bits is increased, the gate scale increases markedly.In actually, even when up to two-dimensional matrix operations are used,the level of freedom in image processing is limited with respect toprocessing using a three-dimensional lattice point data table.

Further, when image processing is performed by an application with analgorithm different from that used in image processing within a camera,it is necessary to previously set coefficients for obtaining a similarprocessing result in the camera. In this case, a large amount of data ofthe three-dimensional lattice point data table, which is not used inimage processing within the camera, must be stored in the ROM of thecamera, and the efficiency of memory usage is seriously lowered.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above problems, andprovides an image capturing apparatus for image processing using alattice point data table, in which a necessary memory capacity forstorage of lattice point data table or the like is reduced.

According to one aspect of the present invention, there is provided animage capturing apparatus for performing digital processing on an imageobtained by image capturing, comprising:

a conversion unit adapted to perform conversion processing on image datausing a lattice point data table;

a holding unit adapted to hold a matrix coefficient set for performingthe conversion processing by matrix operation; and

a setting unit adapted to calculate values of respective lattice pointsof the lattice point data table using the matrix coefficient set, andset the values in the lattice point data table used by the conversionunit.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments (with reference to theattached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention and,together with the description, serve to explain the principles of theinvention.

FIG. 1 is a block diagram showing the entire image capturing apparatusaccording to a first embodiment of the present invention;

FIG. 2 is a block diagram showing the details of an image processor 7 bin the image capturing apparatus in FIG. 1;

FIGS. 3A-3E illustrates color interpolation in image processingaccording to the first embodiment;

FIG. 4 illustrates a three-dimensional lattice point data tableaccording to the first embodiment;

FIG. 5 is a block diagram showing a functional construction for rawimage file generation according to the first embodiment;

FIG. 6 is a flowchart showing raw image file generation processingaccording to the first embodiment;

FIG. 7 is a block diagram showing the construction of an imageprocessing apparatus according to the first embodiment;

FIG. 8 is a block diagram showing a functional construction for raw dataprocessing in the information processing apparatus according to thefirst embodiment;

FIG. 9 is a flowchart showing raw image file processing in theinformation processing apparatus according to the first embodiment;

FIG. 10 is a block diagram showing the functional construction for theraw image file generation according to a second embodiment of thepresent invention;

FIG. 11 is a flowchart showing the raw image file generation processingaccording to the second embodiment; and

FIGS. 12A and 12B illustrate thumbnail image generation according to thefirst embodiment.

DESCRIPTION OF THE EMBODIMENTS

Preferred embodiments of the present invention will now be described indetail in accordance with the accompanying drawings.

First Embodiment

FIG. 1 is a block diagram showing the construction of a digital cameraaccording to a first embodiment of the present invention. In FIG. 1,light passed through an image capturing lens 1 is formed into an imageon an image capture device 4 via an infrared cut-off filter 2 and anoptical LPF 3. As the image capture device 4, a CCD sensor, a CMOSsensor or the like may be used. Generally, photodiode sensors aretwo-dimensionally arrayed on a photoreception surface of the imagecapture device 4. For example, one color is allocated to one sensor by acolor filter where respective R (red), G (green) and B (blue) primarycolor filters are arrayed in a predetermined pattern. Otherwise, it maybe arranged such that the image capture device 4 is prepared incorrespondence with the number of primary colors, and one color isallocated to one image capture device.

In correspondence with depression of a shutter button 19, a CPU 15performs the following image capturing operation. First, lightimage-formed on the image capture device 4 is converted by therespective sensors to electric charges corresponding to incident lightquantities. A signal generated by a timing generator 16 is supplied to ahorizontal driver 17 for horizontal driving and a vertical driver 18 forvertical driving. The horizontal driver 17 and the vertical driver 18supply a driving signal to the image capture device 4 in accordance withthe signal from the timing generator 16. In accordance with the drivingsignals, the electric charges accumulated in the sensors are transmittedfrom the image capture device 4 and sequentially converted to voltagesignals.

The voltage signals are sampled and gain-controlled by a correlateddouble sampling/gain controller (hereinbelow, abbreviated to “CDS/AGC”)5, then converted to digital signals by an A/D converter 6. The imagedata converted to digital signals by the A/D converter 6 is inputtedinto an image processing IC 7. In the image processing IC 7, first, a WBcircuit 7 a calculates data for white balance for the input image data.The data for white balance and the image data are temporarily storedinto the memory 8.

The image data stored in the memory 8 is inputted into the imageprocessing IC 7 again, and subjected to the following three processings.

(1) The image data converted to the digital signals is subjected tolossless compression (reversible compression) by a lossless compressionunit 7 d, and sent as raw data to a CPU bus 10.

(2) The image data converted to the digital signals is changed to athumbnail image having a size smaller than the original image size bydown sampling such as thinning processing by the thumbnail generator 7c, and sent to the CPU bus 10. Note that in the thinning processing, asin the case of FIG. 12B, for example, the down sampling is performed byaveraging the raw image data in block units.

(3) To generate an image for JPEG compression, first, image processingis performed by an image processor 7 b (the details will be describedlater in FIG. 2). Then YCbCr color-space image data, outputted as aresult of the processing, is inputted into a three-dimensional latticepoint data table 7 e. The image data converted by the three-dimensionallattice point data table 7 e is raster-block converted by the JPEGcompression unit 7 f thereby JPEG compressed, and sent to the CPU bus10.

Note that in the present embodiment, the three-dimensional lattice pointdata table is synonymous with a three-dimensional look-up table.

The lossless-compressed raw data and the JPEG-compressed image data arestored into a memory 9 via the CPU bus 10. The CPU 15 generates a rawimage file having the raw data stored in the memory 9 accompanied by theJPEG compressed image. The JPEG compressed image is attached as previewdata of the raw data. The generated raw image file is stored into anexternal memory 14 removably connected via an interface 13. In the aboveconstruction, the three-dimensional lattice point data table 7 e is usedfor generation of a preview JPEG image generated at the same time ofgeneration of the raw data and attached to the raw image file. In thepresent embodiment, as described later, three-dimensional lattice pointdata of the three-dimensional lattice point data table 7 e is generatedfrom high-order matrix coefficients. The matrix coefficients as a basisof the three-dimensional lattice point data table 7 e are also attachedto the raw image file.

Note that a control program to realize the above processing by the CPU15 is stored in the memory 8 or the memory 9.

Next, the image processing performed by the image processor 7 b will bedescribed in more detail with reference to FIG. 2. FIG. 2 is a blockdiagram showing the details of the image processor 7 b.

In FIG. 2, the image data inputted from the memory 8 is first suppliedto the white balance processor 7 b 1. The white balance processor 7 b 1performs white balance processing on the image data using a whitebalance coefficient. Note that the white balance coefficient iscalculated by the CPU 15 based on the data for white balance calculatedby the WB circuit 7 a. The white balance coefficient is stored in thememory 8, and set in the register of the IC 7 in accordance withnecessity. Otherwise, it may be arranged such that the white balanceprocessing is performed on the input image data using a preset whitebalance coefficient (e.g., a white balance coefficient previously set incorrespondence with a light source such as daylight, tungsten,fluorescent lamp or the like). The white-balance-processed image data isinputted into the color interpolation unit 7 b 2, and subjected to colorinterpolation processing. As shown in FIGS. 3A-3C, R, G and B planes(FIG. 3C) are generated from the data patterns (FIG. 3A) and (FIG. 3B)where RGB are arrayed in lattice.

Next, the RGB plane image data is subjected to color optimization by amasking processor 7 b 3 using, e.g., 3×3 matrix operation (expression(1)).R′=m11×R+m12×G+m13×BG′=m21×R+m22×G+m23×BB′=m31×R+m32×G+m33×B  (1)

The image data is supplied via the masking processor 7 b 3 to a gammaconverter 7 b 4. The gamma converter 7 b 4 performs gamma conversion onthe image data. A YUV converter 7 b 5 converts the RGB signal image datagamma-converted by the gamma converter 7 b 4 into YUV signals ofluminance and color difference components, thereby generates Y, Cb andCr planes (FIG. 3D). The conversion to the YUV signals is performed forfalse color processing and edge emphasis processing.

Upon generation of JPEG image, the luminance signal (Y) among the YUVsignals is edge-emphasized by an edge emphasis circuit 7 b 9. Further,the color difference component signals (UV) among the YUV signals aresubjected to noise processing by a median filter 7 b 8.

The edge-emphasized Y signal and the noise-processed UV signals areinputted into the three-dimensional lattice point data table 7 e andcolor-converted. The YUV data outputted from the three-dimensionallattice point data table 7 e is JPEG-compressed by the JPEG compressionunit 7 f.

Next, the three-dimensional lattice point data table 7 e will bedescribed in detail. FIG. 4 illustrates a part of the three-dimensionallattice point data table. In this example, RGB signals are inputted,however, in FIGS. 1 and 2, YUV signals are inputted. The YUV signals maybe converted to RGB signals within the three-dimensional lattice pointdata table 7 e, otherwise, a YUV three-dimensional lattice point datatable may be used.

When [R1, G1, B1]=[155, 155, 140] holds as the input data, the positionin the three-dimensional lattice point data table having nine latticepoints (9 grids) is as shown in FIG. 4, i.e., the data position issurrounded by eight lattice points. In this case, when simple linearinterpolation is performed on the input data, the value of Red can becalculated using data interpolation between positions P1 and P2, datainterpolation between positions P3 and P4, data interpolation betweenpositions P5 and P6, and data interpolation between positions P7 and P8.Note that P1=[128, 128, 128] holds, P2=[160, 128, 128] holds, P3=[128,160, 128] holds, and P4=[160, 160, 128] holds. Further, P5=[128, 128,160] holds. P6=[160, 128, 160] holds, P7=[128, 160, 160] holds, andP8=[160, 160, 160] holds.

Assuming that the value of the [128, 128, 128] lattice point (P1) is[130, 120, 120] and that of the [160, 128, 128] lattice point (P2) is[165, 120, 120], the value in the position [155, 128, 128] is(165−130)+(160−128)×(155−128)+130=159.5  (2)

Similarly, interpolation is performed in other three positions (P3-P4,P5-P6, P7-P8), and the value of Red in the point [155, 155, 140] isdetermined. For example, weighting is performed using inverse proportionof distances between the respective line segments P1-P2, P3-P4, P5-P6and P7-P8 and the point [155, 155, 140] and averaging is performed.These calculations are also performed regarding Green and Blue, thus,RGB values in the point [155, 155, 140] are determined.

As the above calculations are very simple, the circuit scale can be farsmaller than that in the case of high-order matrix operation.

For example, in the case of matrix operation up to third order is:

$\begin{matrix}{{Red} = {{m\; 01 \times R} + {m\; 02 \times G} + {m\; 03 \times B} + {m\; 04 \times R \times R} + {m\; 05 \times G \times G} + {m\; 06 \times B \times B} + {m\; 07 \times R \times G} + {m\; 08 \times R \times B} + {m\; 09 \times G \times B} + {m\; 10 \times R \times R \times G} + {m\; 11 \times R \times R \times B} + {m\; 12 \times R \times R \times R} + {m\; 13 \times R \times G \times G} + {m\; 14 \times G \times G \times B} + {m\; 15 \times G \times G \times G} + {m\; 16 \times R \times B \times B} + {m\; 17 \times G \times B \times B} + {m\; 18 \times B \times B \times B} + {m\; 19 \times R \times G \times B}}} & (3)\end{matrix}$

The calculation processing requires 19 coefficients, 45 multiplicationsand 18 additions. Further, similar calculations are performed for Greenand Blue.

Although the above matrix operation can be realized with hardware, thecircuit scale is inevitably increased. In the present embodiment, thethree-dimensional lattice point data table is not directly stored, but ahigh-order matrix coefficient set as a basis of the three-dimensionallattice point data table is stored within the camera. Then thethree-dimensional lattice point data table is generated using thehigh-order matrix coefficient set. For example, the above m01-m19 matrixcoefficient set is stored, and prior to development processing, R, G andB values of the respective lattice points of the three-dimensionallattice point data table are substituted into the expression (3) and Redvalues in the respective lattice points are obtained. Similarly, Greenand Blue values in the respective lattice points are obtained. In thismanner, the three-dimensional lattice point data is generated, and thegenerated data is set in the three-dimensional lattice point data table7 e.

FIG. 5 is a block diagram showing a functional construction for settingof the three-dimensional lattice point data table according to the firstembodiment. FIG. 6 is a flowchart showing three-dimensional latticepoint data table setting processing by the CPU 15. In FIG. 5, a matrixacquisition unit 51, a mapping unit 52 and an image file generation unit53 are functions realized by executing the control program stored in thememory 8 or 9 by the CPU 15. At step S501, the matrix acquisition unit51 obtains a matrix coefficient set. The matrix coefficient set isstored in, e.g., memory 9. Note that in FIG. 5, plural matrixcoefficient sets are stored in the memory 9, and one appropriate matrixcoefficient set is selected in accordance with an image-captured scene(a landscape scene, a portrait scene or the like) selected by a user. Atstep S502, the mapping unit 52 calculates the values in the respectivelattice points of the three-dimensional lattice data table 7 e using thematrix coefficient set obtained at step S501 and sets the values in thethree-dimensional lattice point data table 7 e. In the presentembodiment, a 9-grid lattice point data table where the respectivelattice point data include three 1-byte values is generated from a 3×19matrix coefficient set.

When an image file is generated using raw data, obtained by losslesscompression or the like directly on output from the CCD or CMOS sensorarray, without execution of the main image processing such as whitebalance processing, the process proceeds from step S503 to step S504. Atstep S504, lossless-compressed raw image data and JPEG-compressed JPEGimage data are generated by the image processing IC 7 and stored intothe memory 9. The image file generator 53 obtains thelossless-compressed raw image data and the JPEG-compressed JPEG imagedata from the memory 9. At step S505, the image file generator 53generates a raw image file using the lossless-compressed raw data, theJPEG image data and the matrix coefficient set obtained from the memory9. The JPEG image data and the matrix coefficient set are recorded inthe raw image file as attendant information. At step S506, the generatedraw image file is stored in the external memory 14. Note that as shownin FIG. 5, when plural types of matrix coefficient sets are stored inthe memory 9, at step S505, the image file generator 53 obtains all thematrix coefficient sets and records them as attendant information in theraw image file. Note that it may be arranged such that only the matrixcoefficient set used in generation of the lattice point data of thethree-dimensional lattice point data table 7 e is recorded as attendantinformation in the raw image file.

Note that as the raw data, any data may be used as long as it is notsubjected to at least main image processing such as white balanceprocessing, color separation processing to separate data into luminanceand color signals, or color interpolation processing on output signalsfrom a Bayer array.

Further, the raw image file is not limited to the above raw image filestructure as long as attendant information including raw data and matrixcoefficient set and JPEG image data are mutually linked.

When a new raw image file is generated, the above steps S503 to S506 arerepeated. Note that when the matrix coefficient set is changed due tochange of image-captured scene or the like, the processing from stepS501 is performed, and a three-dimensional lattice point data obtainedby using a new matrix coefficient set is set in the three-dimensionallattice point data table.

As described above, according to the digital camera of the firstembodiment, as a matrix coefficient set is described in place of athree-dimensional lattice data table in an image file, the data amountof the raw image file can be reduced.

The three-dimensional lattice point data table on the digital cameraside has been described as above, however, the construction to generatea three-dimensional lattice point data table from the above-describedmatrix coefficients can be applied to an application which operates onan information processing apparatus.

FIG. 7 is a block diagram showing the construction of an imageprocessing apparatus. As the information processing apparatus, a generalpersonal computer may be used. In FIG. 7, a CPU 501 realizes respectiveprocessings by executing a program stored in a ROM 502 or RAM 503. TheROM 502 holds a basic input/output system, a boot program and the likein the information processing apparatus. The RAM 503 functions as a mainmemory of the CPU 501. A program installed in an external storage device504, to be executed by the CPU 501, is loaded into the RAM 503. Adisplay 505 performs various displays under the control of the CPU 501.An input device 506 has a keyboard, a pointing device and the like. Aninterface 507 is connectable with, e.g., the external memory 14 of thedigital camera, for reading a raw image file recorded in the externalmemory 14 into the RAM 503 or the external storage device 504.

Various applications are installed into the external storage device 504,and loaded into the RAM 503 upon execution. Note that as the externalstorage device 504, a hard disk is generally used. Hereinbelow, anapplication to process a raw image file generated by the above-describeddigital camera will be described.

FIG. 8 is a block diagram showing a functional construction for imageprocessing realized by the information processing apparatus. Therespective units are functions realized by executing a control programloaded in the RAM 503 by the CPU 15. FIG. 9 is a flowchart showing imageprocessing performed by the information processing apparatus (CPU 15).First, at step S601, a raw image file generated by the above-describedimage file generator 53 is obtained. Then at step S602, the matrixacquisition unit 58 obtains a matrix coefficient set from a header ofthe image file. As described above, when plural matrix coefficient setsare recorded, one of them is selected by the user. For example, theapplication causes the user to select an image-captured scene, and amatrix coefficient set is selected in accordance with the selectedscene. At step S603, the mapping unit 59 calculates values correspondingto the respective lattice points of a three-dimensional lattice pointdata table 512 (three-dimensional lattice point data) using the matrixcoefficient set obtained by the matrix acquisition unit 58. Then, thethree-dimensional lattice point data is set in the three-dimensionallattice point data table 512. Note that the mapping unit 59 generates a33-grid lattice point data table where the respective lattice point datainclude three 2-byte values from a 3×19 matrix coefficient set.

At step S604, the raw data acquisition unit 510 obtains raw data fromthe raw image file, and at step S605, image processing using the latticepoint data table 512 is performed on the obtained raw data, and aprocessed image 513 is obtained. That is, step S605 corresponds to aprocessor using the image processor 511 and the three-dimensionallattice point data table 512.

Note that although not described in the above processing, a previewdisplay of the image is produced using the JPEG image written in the rawimage file (written in the header of the image file).

In the above application, conversion processing using thethree-dimensional lattice point data table 512 can be realized byhigh-order matrix operation. However, it takes much time in such matrixoperation. Accordingly, in the present embodiment, a three-dimensionallattice point data table is generated from a matrix coefficient set andprocessing time is reduced by using the generated three-dimensionallattice point data table. For example, in the case of 33-gridthree-dimensional lattice point data table, calculation for33×33×33=35937 points is performed for RGB, thereby a three-dimensionallattice point data table can be generated. In comparison with matrixoperation for 10,000,000 pixel data, the calculation time in theprocessing of the present embodiment is 1/300. Accordingly, even whenconversion processing using the three-dimensional lattice point datatable is performed thereafter, i.e., even when the generation of thethree-dimensional lattice point data table and the conversion processingusing the table are performed, the calculation time can be reduced.

Further, in a case where a raw image file is structured so as to havethe three-dimensional lattice point data table 512 as above as data,when the data is stored in 16-bit precision, the data amount exceeds 210Kbytes. Further, when such three-dimensional lattice point data isstored for plural sets in the memory in the camera and all the latticepoint data are written as attendant information into a raw image file byimage-sensing data, it is apparent that much time is required for imagefile writing.

Regarding the above construction, according to the present embodiment,the data amount of image file can be reduced and writing time can bereduced by storing a high-order matrix coefficient set (e.g., 3×19matrix coefficients) as a basis of a three-dimensional lattice pointdata table. Further, a three-dimensional lattice point data table havinggrids corresponding to a necessary number of grids can be generated fromthe matrix coefficients. For example, a three-dimensional lattice pointdata table in the camera has nine points per one dimension, while theapplication can generate a three-dimensional lattice point data tablehaving 33 points per one dimension from the same matrix coefficient set.Accordingly, high precision can be maintained in the application. Thereis a difference in precision between color representation inside thecamera and that in the application, however, it is effective thatpriority is given to the color representation precision in theapplication, while priority is given to high-speed processing onamount-reduced data inside the camera.

Second Embodiment

Next, the image processing in the digital camera according to a secondembodiment will be described with reference to FIG. 10.

The digital camera itself performs development processing and generatesJPEG data, or the digital camera generates raw data. The raw data isobtained by performing lossless compression or the like on output fromCCD or CMOS sensor array without execution of main image processing suchas white balance processing. Such raw data is used in desirable imagingby image processing with an information processing apparatus outside thecamera. The image processing on the raw data in the informationprocessing apparatus may be the same as the image processing within thecamera, however, image processing in the information processingapparatus may not especially be the same as the image processing withinthe camera. It may be arranged such that image processing which cannotbe performed with hardware is realized on an application so as toprovide a more excellent image. As an example, in the applicationsoftware shown in the first embodiment, the number of lattice points ofthe three-dimensional lattice point data table is not necessary the sameas that of the hardware of the camera.

However, in the application software, although the bit precision can beeasily increased, the processing speed is obviously lower than that inthe hardware.

In the application, image processing different from the image processinginside the camera can be realized by increasing the processing speedwith another method and further handling inconvenience. On the otherhand, when the image processing inside the camera and that in theapplication are different, if a common three-dimensional lattice pointdata or common high-order matrix data is used, the results of processingmay be different. Accordingly, as shown in the memory 9 in FIG. 10,three-dimensional lattice point data for camera (9 a) and a high-ordermatrix coefficient set (9 b) as a basis of three-dimensional latticepoint table data for the application, linked with each other, are storedinside the camera. The matrix coefficient sets are set such that theapplication can output the same image as a JPEG image outputted from thedigital camera main body.

Accordingly, the processing by the digital camera (CPU 15) according tothe second embodiment is as shown in FIGS. 10 and 11. Note that a datasetting unit 61 and an image file generator 62 in FIG. 10 are functionsrealized by executing a control program by the CPU 15. First, at stepS701, the data setting unit 61 obtains three-dimensional lattice pointdata to be used from the memory 9, and sets the data in thethree-dimensional lattice point data table 7 e. When pluralthree-dimensional lattice point data exist, as in the case of the firstembodiment, three-dimensional lattice point data to be used is selectedin correspondence with, e.g., an image-captured scene selected by theuser. The three-dimensional lattice point data is held in the memory 9as shown in FIG. 10. In the memory 9, the three-dimensional latticepoint data and the matrix coefficient sets are respectively linked witheach other.

When an image file using data obtained by lossless-compressing raw datais generated, the process proceeds from step S702 to step S703. At stepS703, an image file generator 62 obtains the lossless-compressed rawdata and the JPEG-compressed image data from the memory 9. As describedabove, the lossless-compressed raw data and the JPEG-compressed imagedata are generated by the image processing IC 7 and stored in the memory9. At step S704, the image file generator 62 obtains a matrixcoefficient set corresponding to the three-dimensional lattice pointdata table 7 e used in the JPEG compression from the memory 9. Then atstep S705, the image file generator 62 generates an image file using thelossless-compressed raw data, the JPEG-compressed image data, and thematrix coefficient set obtained at step S704. Then at step S706, thegenerated image file is recorded in the external memory 14. Note that,as in the case of the first embodiment, when there are plural matrixcoefficient sets in the memory 9, all the matrix coefficient sets may beattached to the raw image file, or it may be arranged such that only thematrix coefficient set used in the generation of the lattice point dataof the three-dimensional lattice data table 7 e is attached.

When a new raw image file is generated, the above steps S702 to S706 arerepeated. Note that when the three-dimensional lattice point data tableis changed due to change of image-captured scene or the like, theprocessing from step S701 is performed, and the three-dimensionallattice point data table is set using new three-dimensional latticepoint data.

As described above, according to the second embodiment, an image signalis subjected to image processing by the image processor 7 b, andthree-dimensional lattice point data to be set in the three-dimensionallattice point data table 7 e is obtained from the memory 9. Since it isunnecessary to calculate the three-dimensional lattice point data from amatrix coefficient set as in the case of the first embodiment, imagestorage processing in the camera can be performed at a high speed. Onthe other hand, as in the case of the first embodiment, a matrixcoefficient set is stored in a raw image file. Accordingly, theapplication software on the information processing apparatus sideperforms a similar operation to that in the first embodiment.

As described above, according to the second embodiment, even whendifferent image processing methods are used, as a pair ofthree-dimensional lattice point data and high-order matrix data are usedin the respective image processings, images having the same colorrepresentation can be obtained.

Note that in the second embodiment, a JPEG image and a matrixcoefficient set are attached to a raw image file, further,three-dimensional lattice point data used in the generation of the JPEGimage may be recorded in the file. In this case, as thethree-dimensional lattice point data is attached to the file, theapplication can grasp the three-dimensional lattice point data used inthe generation of the JPEG image, and can use and reproduce the data.

As described above, according to the first embodiment, necessary latticepoint data of three-dimensional lattice point data table can becalculated by performing high-order matrix operation as a basis of thethree-dimensional lattice data table. Accordingly, in a digital camerahaving a three-dimensional lattice point data table, it is unnecessaryto directly hold the lattice point data used in the three-dimensionallattice point data table. Further, when data converted using thethree-dimensional lattice point data table stands among lattice points,as calculation can be made from peripheral lattice points including theinput data, the interval between lattice points can be rough.Accordingly, the amount of data stored inside the camera can beminimized. Further, according to the second embodiment, asthree-dimensional lattice point data utilized inside the camera and amatrix coefficient set to be attached to a raw image file are held, itis unnecessary to calculate the three-dimensional lattice point datainside the camera. Further, the matrix coefficient set utilized by theapplication and the three-dimensional lattice point data table utilizedinside the camera can be adapted to the respective image processings bythe application and the camera. Accordingly, images having the samecolor representation can be obtained by both image processings.

Further, as the matrix coefficients include data depending on theindividual camera or camera model such as bias error in sensor outputand color filter characteristic. Accordingly, the characteristics ofindividual camera or camera model are absorbed in the matrixcoefficients, the user can perform appropriate color representationmerely by selecting a preferred image-captured scene withoutconsideration of such characteristics of individual camera or cameramodel. In the application software, the same image as that obtained byimage sensing a predetermined chart can be obtained.

Note that the data of the three-dimensional lattice point data table maybe L*, a*, b* or X, Y, Z as well as Red, Green, Blue or Y, U, V.Further, the three-dimensional lattice point data table 7 e ispositioned in the last of the calculation processing forcolor-representation, however, the three-dimensional lattice point datatable as described above may be used in other conversion processing.Further, an image file is delivered from the digital camera to theinformation processing apparatus via the external memory, however, theimage file may be transferred using communication such as USB. Further,the information processing apparatus may be a printer. Further, in theabove respective embodiments, the application of the present inventionto the three-dimensional lattice point data table (three-dimensionallook-up table) has been described, however, the dimension of the latticepoint data table is not limited to the three dimension. For example, thepresent invention is apparently applicable to a four or more dimensionallattice point data table, or two-dimensional or one-dimensional latticepoint data table (two-dimensional look-up table or one-dimensionallook-up table).

The embodiments have been described in detail as above, however, thepresent invention can be implemented as a system, an apparatus, amethod, a program or a storage medium. More particularly, the presentinvention can be applied to a system constituted by a plurality ofdevices or to an apparatus comprising a single device.

Note that the present invention can be implemented by supplying asoftware program directly or indirectly to a system or apparatus,reading the supplied program code with a computer of the system orapparatus, and then executing the program code, thereby the functions ofthe foregoing embodiments are implemented. In this case, the suppliedprogram corresponds to the flowcharts in the figure described in theembodiments.

Accordingly, since the functions of the present invention areimplemented by the computer, the program code installed in the computeralso implements the present invention. In other words, the claims of thepresent invention also cover a computer program for the purpose ofimplementing the functions of the present invention.

In this case, as long as the system or apparatus has the functions ofthe program, the program may be executed in any form, such as an objectcode, a program executed by an interpreter, or script data supplied toan operating system.

Example of storage media that can be used for supplying the program area floppy (registered trademark) disk, a hard disk, an optical disk, amagneto-optical disk, an MO, a CD-ROM, a CD-R, a CD-RW, a magnetic tape,a non-volatile type memory card, a ROM, and a DVD (a DVD-ROM and aDVD-R).

As for the method of supplying the program, a client computer can beconnected to a website on the Internet using a browser of the clientcomputer, and the computer program of the present invention or anautomatically-installable compressed file of the program can bedownloaded to a recording medium such as a hard disk. Further, theprogram of the present invention can be supplied by dividing the programcode constituting the program into a plurality of files and downloadingthe files from different websites. In other words, a WWW (World WideWeb) server that downloads, to multiple users, the program files thatimplement the functions of the present invention by computer is alsocovered by the claims of the present invention.

It is also possible to encrypt and store the program of the presentinvention on a storage medium such as a CD-ROM, distribute the storagemedium to users, allow users who meet certain requirements to downloaddecryption key information from a website via the Internet, and allowthese users to decrypt the encrypted program by using the keyinformation, whereby the program is installed in the user computer.

Besides the cases where the aforementioned functions according to theembodiments are implemented by executing the read program by computer,an OS or the like running on the computer may perform all or a part ofthe actual processing so that the functions of the foregoing embodimentscan be implemented by this processing.

Furthermore, after the program read from the storage medium is writtento a function expansion board inserted into the computer or to a memoryprovided in a function expansion unit connected to the computer, a CPUor the like mounted on the function expansion board or functionexpansion unit performs all or a part of the actual processing so thatthe functions of the foregoing embodiments can be implemented by thisprocessing.

According to the present invention, in an image capturing apparatuswhich performs image processing using a lattice point data table, thememory capacity necessary for storage of the lattice point data tablecan be reduced.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Laid-Open No.2005-236734, filed on Aug. 17, 2005, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. An image capturing apparatus for performingdigital processing on an image obtained by image capturing, theapparatus comprising: a storing unit configured to store, in advance ofobtaining the image by image capturing, (a) a plurality of lattice pointdata sets for being set in a lattice point data table to performconversion processing inside the apparatus and (b) a plurality of matrixcoefficient sets as bases for a plurality of lattice point data sets forperforming conversion processing with a matrix operation outside theapparatus, wherein each of the matrix coefficient sets is a basis forgenerating a lattice point data set in which a number of lattice pointsper one dimension is larger than a number of lattice points per onedimension in each of the stored plurality of lattice point data sets; aselection unit configured to select a lattice point data set from theplurality of lattice point data sets stored in said storing unit; aconversion unit configured to perform conversion processing on imagedata using the lattice point data set selected by said selection unit;and a file generation unit configured to generate an image file whichincludes (a) the image data, and (b) a matrix coefficient set stored insaid storing unit, as attendant information in the image file, whereinthe matrix coefficient set included in the image file corresponds to thelattice point data set which is selected by said selection unit and isconfigured to generate the lattice point data set by a matrix operation.2. The apparatus according to claim 1, wherein said selection unitselects the lattice point data set in accordance with an image-capturedscene.
 3. The apparatus according to claim 1, wherein the image fileincludes raw image data as the image data in the image file.
 4. Theapparatus according to claim 3, wherein the image file includescompressed image data in the image file.
 5. The apparatus according toclaim 1, wherein the lattice point data table is a three-dimensionallattice point data table.
 6. The apparatus according to claim 1, whereinsaid conversion unit performs interpolation of a data point withinlattice points of the lattice point data set.
 7. The apparatus accordingto claim 1, wherein the matrix coefficient sets are for calculatingvalues of respective lattice points of the lattice point data tablewithout performing a matrix definition processing.
 8. An imageprocessing method for an image capturing apparatus for performingdigital processing on an image obtained by image capturing, the methodcomprising: a selection step of selecting a lattice point data setstored in a storing unit that stores, in advance of obtaining the imageby image capturing, (a) a plurality of lattice point data sets for beingset in a lattice point data table to perform conversion processinginside the apparatus and (b) a plurality of matrix coefficient sets asbases for a plurality of lattice point data sets for performingconversion processing with a matrix operation outside the apparatus,wherein each of the matrix coefficient sets is a basis for generating alattice point data set in which a number of lattice points per onedimension is larger than a number of lattice points per one dimension ineach of the stored plurality of lattice point data sets; a conversionstep of performing conversion processing on image data using the latticepoint data set selected in said selection step; and a file generationstep of generating an image file which includes (a) the image data, and(b) a matrix coefficient set stored in the storing unit, as attendantinformation in the image file, wherein the matrix coefficient setincluded in the image file corresponds to the lattice point data setwhich is selected in said selection step and is configured to generatethe lattice point data set by a matrix operation.
 9. A non-transitorycomputer-readable memory storing a control program for executing theimage processing method of claim 8 by a computer.
 10. The apparatusaccording to claim 1, wherein the lattice point data table is athree-dimensional lattice point data table, and wherein the matrixcoefficient set included in the image file is used by the apparatus togenerate the lattice point data set which is selected by said selectionunit and included in the image file.
 11. The apparatus according toclaim 10, wherein the image data included in the image file compriseslossless-compressed image data, and wherein the image file furtherincludes JPEG image data as attendant information.
 12. The apparatusaccording to claim 10, wherein the plurality of matrix coefficient setsstored in said storing unit are included in the image file as attendantinformation.
 13. The apparatus according to claim 1, wherein each of theplurality of matrix coefficient sets is a set of coefficients of termsin an expansion equation for a matrix operation of a predetermined orderof 2 or more.
 14. The apparatus according to claim 1, wherein thelattice point data table stored by said storing unit indicates arelationship between image signals before and after conversion in acolor conversion processing.